情态动词一canmaymust的用法

must / must not
must的用法: 1. must表示必须
You must do your homework first. 2. must表示 “一定”(肯定性推测 )
语气较强 He must be at home.
must / must not
must not的用法:
1. mustn’t表示禁止(不准；不允许) You mustn’t smoke here.
Did he have to do it? You don‘t have to go there. （不必，不需要）
‖ needn’t
六neeቤተ መጻሕፍቲ ባይዱ的用法
• 后加动词原形 表示需要，必须，用于否定和疑问句 否定：needn’t（不需要）， 疑问将need提前
疑问句回答：同must Need we return the magazines today？
1. S1 C__a_nKitty s_p_e_l_l ? S2 Y__es_,_s_h_e_c_a_n____.
2. S1 C__a_n_ Kitty a_d__d_? S2 _N_o_,_s_h_e__c_a_n_’t__.
may / may not
may的用法: 1. 表示允许(可以) 也可用might更委婉
6._____C__a_n______you please open the window?
9. Nobody __c__a_n______live without air. 10.__C__a_n____he speak Chinese ?Yes ,a little. 11. The book __m__u__s_t__ be returned before Saturday. 12.__M__a__y____I come in ?Yes ,please. 13. You _m__u__s_t__give up smoking at once. It’s bad
2. 以must开头的疑问句，其否定回答 要用needn’t. -- Must I clean the classroom now? -- Yes, you must. No, you needn’t.
五.have to的用法
• 表示客观需要 “不得不，必须”
I missed the train, so I had to take a taxi. 在疑问句和否定句中，have to需借助助动词 do ，
May /Might I come in? 2. 表示推测 (可能) ----通常用于肯定形式
She may be still waiting for us. 3. 表示祝愿
May you have a happy weekend.
may / may not
may not的用法: ●以may开头的疑问句，其否定回 答用can’t或 mustn’t。 --May I go home now? --Yes, you may. No, you can’t/mustn’t.
3.My grandma is ill. You __c_a_n_’_t _ talk so loudly here .
4.I can’t play with you. I ___m_u_s_t____finish my homework first.
5.I____m_u_s_t___ get up early tomorrow. because I have a meeting.
yes， you must./ no, you needn’t.
You need not do this。 注：用于肯定句时，常作实意动词用：need to do sth
What do the signs mean? Do you know?
You must not cycle. You must not enter. You must be careful. You must turn left.
for your health.
14. Excuse me ._M__a__y____I ask you a question?
15. __C__a_n_____you tell me where the station is ? 16. M___u_s_t__ I finish the work now ?No, you _n_e_e__d_n__’t_.
情态动词can, may, must的用法
Modal verbs 情态动词
• 情态动词后接动词原形; • 没有人称和数的变化; • 不能单独作谓语, 与后面的动词共同作谓语; • 其否定形式在后面直接加not。
Modal verbs 情态动词
• can / can not • may / may not • must / must not
You must pay ten yuan. You must keep silent. You must not smoke. You must not turn right.
Ⅰ.用适当的情态动词填空：。
1.I can play football. ___C__a_n____you swim? 2.Don’t worry. You ___m__a_y__ return me this book tomorrow.
Answers:
1. May I carry your bag for you? 2. May I open the door? 3. May I get you a chair? 4. May I switch on the TV? 5. May I borrow your new bicycle?
can / can not
1. 表示能力(会) Mary can speak English, but she can not speak French.
2. 表示允许(可以) 也可用could (不是过去式)更委婉 Can /Could I use your dictionary?
3. 表示推测 (可能 ) ----通常用于否定形式 He can’t be in the office. I saw him go out just now.